In the modern world of automation, almost every device or machine includes moving elements. Often, these moving elements are in a location that is inaccessible while operating. Therefore, there is a great importance in having advanced warning that maintenance is required. This advanced warning is typically in the form of position awareness for each element. This allows problems and malfunctions to be isolated and replaced with minimal effort, expense, and down-time.
The success of a system is dependent on the ability to measure a position for each element and communicate this position to a remote location. Varying pressure from a pneumatic or hydraulic source typically controls the position of the moving device.
Currently, a positional control system comprises a controller device, control means, a device under control, a wired communications network and a device to measure the position. The position-measuring device measures position data of an element of the device under control and communicates this information to a control device using a communications cable. Additionally, the position-measuring device includes an external power source to power the device.
However, the current requirement for an external power source to be connected to the position-measuring device creates a problem in a harsh environment where it is impractical or impossible to install electronics and wires to provide a power source or where an external power source is unavailable.
Another position control system includes a controller device, control means, a device under control and a device to measure pressure. The position of the device is controlled by varying the fluid pressure. Thus the position control of a remote device is achieved indirectly by controlling pressure of a fluid.
In this case there is a high degree of uncertainty as to whether the device is actually moving as the pressure is varied and it is impractical or undesirable to utilize a wired position sensor.
Accordingly, there is a need for a position feedback device that can create or derive its own power source based upon local environments and movement conditions such that there is no need for electrical wiring. Further, there is a need for a wireless position feedback device to be able to communicate with a control device without the need of wires.
Accordingly, there is a need for a wireless position feedback device that is capable of generating its own power and can accurately measure the position of a device under monitoring.